def _get_roll_nonmissing(self, x: xr.Dataset, mode: str, roll_dim: str, roll_size: int) -> xr.DataArray:
"""Generate a mask f missing values in a moving window.
Parameters
----------
x: xr.Dataset
The dataset.
mode: str
Whether all variables must be present or any.
roll_dim : str)
The dimension to apply moving window on.
roll_size : int
The moving window size.
Returns
-------
xr.DataArray: The mask with 1 for valid, 0 for invalid.
"""
if mode == 'any':
fn = lambda x: x.any('variable')
elif mode == 'all':
fn = lambda x: x.all('variable')
else:
raise ValueError(
f'arg `mode` must be one of `all` | `any`, is `{mode}`.'
)
return fn(x.to_array('variable').notnull()).astype(int).rolling({roll_dim: roll_size}).sum() == roll_size
